On: Building muscle doesn't require lifting heavy weights

[billswift]

It is just the other way around for me. I ride in a fairly high gear with low cadence, and get a muscular burn in my thighs, because when I try to push a higher cadence in easier gears my knees start hurting.

[phsr → billswift]

You should go to a local bike shop and make sure your bike is fitted properly. It definitely should not hurt your knees at a higher cadence